Method for preparing cracker balls



United States Patent 3,195,394 METHQD Fil h PREPARENG CRACKER BALLS Toshio Tamara, 464 Kishi, Shimadwshi, Japan No Drawing. Filed Aug. 17, 1964, Ser. No. 39ii,ll4 1 Claim. (Ci. 86-1) The present invention relates to an improved method for preparing cracker balls.

In a prior art method for preparing cracker balls to be employed as fireworks, potash chlorate is firstly mixed with realgar to form a base explosive mixture and the base explosive mixture is then rendered into a slurry state with addition of water in a suitable amount thereto so as to prevent the mixture from exploding accidentally. The slurry explosive mixture is further added coarse grain sand thereto in order to accelerate the generation of frictional heat by the explosive mixture and the resultant sand containing explosive mixture is stirred so that the base explosive materials may evenly adhere on the overall surface of the sand. Thus obtained explosive product is divided into many small masses (each mass has a size substantially equal to that of one soybean) and each mass is wrapped with a sheet of thin Japanese paper and the wrapped explosive mass is further wrapped with another sheet of thin Japanese paper on one surface of which starching material has been applied. The dually wrapped explosive product is manually formed into a desired ball shape and its surface is colored and finally dried. How ever, all of the various procedures referred to above have to be manually carried out and accordingly, such a prior art method for preparing cracker balls is quite inefficient. Especially the wrapping process is complicated because a mass of explosive product has to be firstly wrapped with a sheet of thin Japanese paper (pinch paper) and then further with another sheet of paper which has starching material applied on one surface (cover paper). The above is one important drawback of the prior art method for preparing cracker balls.

Accordingly, the object of the present invention is to provide a novel method for preparing cracker balls which can eliminate the above-mentioned drawback associated with the prior art method.

According to the present invention, there is provided an improved method for preparing cracker balls which consisting of mixing powdery potash chlorate with powdery realgar to form a base explosive mixture, of adding water to said explosive mixture to render the mixture into slurry state, and of adding hard granular material to said slurry explosive mixture so as to evenly distribute said granular additive within the slurry explosive mixture, characterized in that said method further consisting of diving said granular additive containing explosive mixture into many small masses each of which containing a substantially same amount of the explosive mixture, of freezing said explosive mixture masses, of individually covering said frozen explosive mixture masses with a gas permeable material such as paper or powdery pulp, and of drying said covered explosive mixture masses.

In forming many small masses of the explosive mixture in accordance with the method of the present invention, as described in the typical example of the present method given below a pattern plate having a plurality of identical size holes is employed and the explosive mixture is filled in the holes. The explosive mixture within the holes is then frozen in situ whereby many identically sized mixture masses can be simultaneously formed. Since thus formed explosive mixture masses are solidified by being frozen the masses can be easily covered with a gas permeable material such as paper or powdery pulp, and in ad- Patented July 26, 1965 ice dition when the frozen masses are dried the moisture contained within the masses is evaporated and at the same time the explosive mixture masses shrink forming voids therein. As a result when thus obtained explosive product is employed for its intended purpose the hard granular additive therein can positively move by impact action to generate frictional heat resulting in easy explosion of the explosive product.

The following is one typical example in which the method by the present invention is carried out.

For example: 6 volume by weight powdery potash chlorate and 4 volume by weight powdery realgar are placed into a rotary vessel and water is added to the base explosive mixture while the vessel is being rotated to render the base mixture into a slurry state. Then 100 volume by weight sand having a diameter of about 2 mm. is added to the slurry base explosive mixture within the vessel and the base mixture and sand are fully mixed while being stirred so as to form an explosive mixture product. Thus obtained explosive mixture product is filled in many circular holes which are formed in a pattern plate and have a dimension of 6 mm. in diameter and 6 mm. in depth and the explosive product filled within the holes is then frozen in a refrigerating room maintained at a temperature of 30 C. for about 20 minutes. Thereafter the frozen mixture product is taken out of the refreezing room and removed from within the holes thereby to obtain solid granular explosive masses. The solid granular explosive masses are dropped onto powdery starching material so as to have the starching material adhered on the surface of the masses. Thus adhered starching material melts by the moisture contained in the explosive masses and forms a film on the surface of the masses. As soon as such a film has been formed on each mass, about mesh of powdery pulp is applied on the starching layer and is caused to adhere thereon. Such powdery pulp is repeatedly applied on the masses by means of a water soluble starching material until the thickness of the pulp powder layer becomes about 2 mm. The surface of the pulp applied explosive masses is colored as desired and air-dried for about 8 hours thereby to obtain pulp powder coated explosive products having a diameter of about 7 mm. on a mass production program.

It should be understood that the present invention is not limited to the details of the foregoing descriptions and illustration of the typical example of the invention, except as expressed hereinafter in the claim.

What is claimed is:

A method for preparing cracker balls which consists of mixing powdery potash chlorate with powdery realgar to form a base explosive mixture, of adding water to said explosive mixture to render the mixture into a slurry state, and of adding hard granular material to said slurry explosive mixture so as to evenly distribute said granular additive within the slurry explosive mixture, characterized in that said method further consists of dividing said granular additive containing explosive mixture into many small masses each of which contains a substantially equal amount, freezing said masses of explosive mixture, covering said frozen masses of explosive with air-permeable substance such as paper or pulp powder and drying said explosive mixture masses.

References Cited by the Examiner UNITED STATES PATENTS 2,061,854 11/36 Sherman 10237 BENJAMIN A. BORCHELT, Primary Examiner. 

